iOS自定义转场动画``` 1,我们需要自定义一个遵循的协议的动画过渡管理对象，并实现两个必须实现的方法： ``` ``

1,我们需要自定义一个遵循的<UIViewControllerAnimatedTransitioning>协议的动画过渡管理对象，并实现两个必须实现的方法：

 //返回动画事件  
 - (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;
 //所有的过渡动画事务都在这个方法里面完成
 - (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

2,我们还需要自定义一个继承于UIPercentDrivenInteractiveTransition的手势过渡管理对象，我把它成为百分比手势过渡管理对象，因为动画的过程是通过百分比控制的

3,成为相应的代理，实现相应的代理方法，返回我们前两步自定义的对象就OK了 ！

模态推送需要实现如下4个代理方法，iOS8新的那个方法我暂时还没有发现它的用处，所以暂不讨论

 //返回一个管理prenent动画过渡的对象
 - (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source;
 //返回一个管理pop动画过渡的对象
 - (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed;
 //返回一个管理prenent手势过渡的对象
 - (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id <UIViewControllerAnimatedTransitioning>)animator;
 //返回一个管理pop动画过渡的对象
 - (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id <UIViewControllerAnimatedTransitioning>)animator;

导航控制器实现如下2个代理方法

 //返回转场动画过渡管理对象
 - (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                   interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);
 //返回手势过渡管理对象
 - (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                            animationControllerForOperation:(UINavigationControllerOperation)operation
                                         fromViewController:(UIViewController *)fromVC
                                           toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);  
标签控制器也有相应的两个方法


 //返回转场动画过渡管理对象
 - (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
               interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController NS_AVAILABLE_IOS(7_0);
 //返回手势过渡管理对象
 - (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
     animationControllerForTransitionFromViewController:(UIViewController *)fromVC
                                       toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);